Gene targeting is a genetic technique for replacing an existing gene with a mutated (changed) one. It can be done in lab mice or some other model organism.
The method can be used to delete a gene, remove control sections, add a gene, and introduce point mutations.
Gene targeting can be permanent or conditional. Conditions, for example, can be a specific time during development in the life of the organism or limited to a specific tissue.
To date, this method has been applied to a number of species including Drosophila melanogaster, tobacco, corn, human cells. mice, and rats.